Phase-change materials (PCM) are capable of transforming from a crystalline phase to an amorphous phase. These two solid phases exhibit differences in electrical properties, and semiconductor devices can advantageously exploit these differences. Given the ever-increasing reliance on radio frequency (RF) communication, there is particular need for RF switching devices to exploit phase-change materials. However, the capability of phase-change materials for phase transformation depends heavily on how they are exposed to thermal energy and how they are allowed to release thermal energy. For example, in order to transform into an amorphous state, phase-change materials may need to achieve temperatures of approximately seven hundred degrees Celsius (700° C.) or more, and may need to cool down within hundreds of nanoseconds.
Heating elements in PCM RF switches often contribute to parasitic capacitances associated with RF frequencies and result in performance tradeoffs. These RF performance tradeoffs can result in wasted power, low breakdown voltage, and decreased reliability. Fabricating heating elements without significant RF performance tradeoffs becomes complex, especially where the PCM RF switch is designed primarily around thermal performance. Accordingly, accommodating PCM in PCM RF switches can present significant manufacturing challenges. Specialty manufacturing is often impractical, and large scale manufacturing generally trades practicality for the ability to control device characteristics and critical dimensions.
Thus, there is a need in the art for reliable PCM RF switches having improved RF performance.